Furnace



Jan. 18, 193s. I

R. M. PARSONS 'I 2,105,500 FURNACE y Filed April 25. 1935 5 Sheets-Sheet2 4 ZZ i I. ZZ

Z1 Z5 Z5 INVENTOR Edi/ farsa/zr BY l/ Jn. 18, 1938. R M, PARSQNS2,105,500

FURNACE Filed April 25, 1935 3 SheetS-Sheei'I 5 h N a Patented jan. 18,1938 Hurrah sraras .FURNACE Ralph M. Parsons, Mount Vernon, Ohio,assignor to The Ralph M. Parsons Company, Mount Vernon, Ohio,a'corporation of Delaware Application April 25, 1935, serial No. 18,125

11 claims.

'Ihis invention relates to furnaces and more particularly to tube stillsfor use in oil cracking or refining plants.

An object of the invention is to improve the details of construction andmethod of operation of a furnace of the above type.

In accordance with the present invention the furnace is provided with anelongated combustion chamber having a bank of radiant heat tubes locatedcentrally thereof and dividing the comlbustion chamber into twosections. Rows of burners are located on each sidepof the radiant heattubes for'applying heat equally to the two sides thereof. The combustiongases pass over the radiant heat tubes and into a convection chamberwhich is located in line with the normal ow of gases and is of smallercross-section than the combustion chamber so that the gases passtherethrough at an increased velocity.

In one embodiment, the combustion chamber is elongated vertically withthe bank of radiant heat tubes extending vertically from the floor atabout the center line thereof. The burners are mounted in or near thefloor in a position to heat the side walls to radiance whereby theradiant heat is reradiated onto the tubes. v vection chamber is locatedover the combustion chamber and is joined thereto by sloping walls whichdefine a. passage for the combustion gases.

Y A feature of the invention consists in the provision of a member inalignment with the radiant heat tubes, which is stream lined in thedirection of gas iiow so as to dir'ect the gases into the convection'chamber with 'a minimum of turbulence and to cause a uniformdistribution of gases over the convection tubes.

Another feature consists in the provision of air passagesl or channelscn the outside of the furnace Walls which are so arranged that the air40 for combustion is caused to pass downwardly over the walls on its wayto the burners. A further feature consists in the truss structure whichis adapted to support the walls, the convection tubes and the hood. I

'45 Various other features will'be apparent as the nature of theinvention is more fully disclosed.

Although the novel features which are believed to be characteristic ofthis invention will be more particularly pointed out in the claimsappended hereto, the invention itself, as to its objects and advantages,and the manner of its operation, will be better understood b y referringto the following description, taken in connection with the accompanyingdrawings forming a part fthereof, in which:

The con- (C1. ISS- Fig. i is a transverse vertical section through afurnace illustrating an embodiment of the present invention;

Fig. 2 is an end elevation thereof Fig. 3 is a longitudinal sectiontaken along 5 the line 3-3 of Fig. 1 but with parts of the tubesbroken'away to show the burners;

Fig. 4 is a detail view of a part of the truss structure; and I Fig. 5is a section taken on the line 5-5 of 10 Fig. `4.

Specic terms are used herein for convenience of description but they aret'o be interpreted as broadly as the state of the art will permit.

l Referring to the drawmgs more in detail, the 15 invention is shown as'applied to a furnace comprising a vertically elongated combustionchamber i0 havin'g side walls II and end walls I2, and a convectionchamber I3 of smaller crossy section than the combustion chamber I0 and20 located directly thereover. The convection chamber I3 is providedwith side walls i4, which may be joined to the side walls Il by slopingwalls i6. A hood Il is mounted above the convection chamber I3 and isadapted to conduct 25 exhaust gases to a stack I8.

The walls I l and l2 may be supported upon side and end foundations 2|and 22 respectively, such as brickwork. A plurality of spaced centralpiers 23 are arranged to support lower tube sheets 24 30 which arepreferably made of a heat resisting material such as alloy steel. Theymay comprise four angles which are secured together, as by welding, toprovide a rigid structure. At their lower ends-they may be provided withared bracV 35 ing members 25 which rest upon the central piers 23. Thetwo end tube sheets 24a may be insulated on the outside only, as byinsulation 24h, to prevent escape of heat. 'Ihe tube sheets 24 may beapertured to receive two vertical rows 40 of radiant heat tubes 26. Attheir lower ends they may be apertured to receive an additional set oftubes 2l such as boiler tubes for utilizing the heat in the lower partof the furnace below the zone of radiance or cooling the bottoms of 45tube supports 24.

A cradle member 28 may be mounted on the tops of the tube sheets 24.This cradle member. adapted to receive and support a guide member 29having a tear drop or stream lined sec- 50 tion, which is adapted todirect the gases from .the combustion chamber IB to the convectionchamber I3 with a minimum of turbulence vand to cause uniformdistribution of such gases in the convection chamber. The guide member29 55 passage of the gaseous fuel and air.

is preferably hollow and may be made of any suitable heat resistingmaterial such as rebrick,

reclay or concrete.

A floor 32 may be supported vby a plurality of transverse beams 33,mounted upon longitudinal girders 34, whichrest upon the sidefoundations l 2l and upon the central piers 23. Burners 35 may also besupported by the transverse beams 33. These burners may comprise a blockof refractory material having a flared central bore 36 for The bores 36are preferably formed in the shape of a Venturi tube. When so formedthey constitute an eiicient mixing device for the fuel and air.Furthermore, the flow of fuel may induce the flow of air for combustionthereby eliminating the necessity for a forced air feed. The burners maybe located in rows extending longitudinally of the furnace on both sidesof the radiant heat vt`ubes 26 and'may be directed somewhat toward theside walls Il so as to heat the walls to radiance and so as to preventthe direct heat of the flame from' being applied to` the radiant heattubes.

yThe part lla of the side walls I I, against which the flame from theburners is directed, may be thicker than the upper part II b of thewalls which is not required to withstand as much heat and is not reliedupon to absorb the radiant heat and to reradiate the'same to the tubes.The side walls I4 of the convection chamber I3 may be of still thinnerconstruction as they are subjected only to convection heat. Theslopingwalls I6 are preferably similar to the upper part lilb of theWalls II' although the walls may taper in thickness from the hottestportion, near the burners 35,v to the coolest portion, at the top orbottom', if such construction is desired for purlithic in which case thewalls themselves are sub" poses of economy. The walls may have an outercovering I 4a of impervious material such as plaster board or metal toprevent escape of air or combustion gases, unless the walls aremonostantially air and gas tight.

For supporting the walls I4 and I6, upper tube sheets 60 and hood I1,there may be provided a framework comprising side buck stays 4 5 and endbuck stays 46 which may rest upon the foundations 2| and 22respectively. The side walls. y II may be anchored to the lside buckstays 45 at convenient points. A set of vertical truss members 41 andinclined truss members 48 are positioned adjacent the side walls I4 andthe sloping Walls I6 respectively. Suitable anchors, not shown, may-beprovided to secure the walls I4 and I6 to these truss members.

The vertical truss members 41r form a part of a vertical truss,comprising top member 49, bottom member 50' and bracing members 5I.Thevtops of the buck stays 45 are joined by a member 52 forming, withthe top member 49, and with bracing members 53, an upper horizontaltruss. A longitudinal member 54, secured to the side buck stays 45,forms, with the bottom member 56 and with bracing members 55, a lowerhorizontal truss. The inclined truss members 48 are joined tosthe sidebuck stays 45 and to the vertical truss members 41, as by Welding, toform a rigid structure. End top members 66, secured to the end 'buckstays 46, are joinedlto the members 52 to form a frame extendingentirely around the top of the furnace. Lower 'vertical angles 51,inclined angles and upper vertical angles 59 may be joined tothe endtruss members to form the end l .heat tubes 26, preferably from top tobottom,

frames of thefurnace.

Upper tube sheets 60` are provided with hangers 6I which are supportedby members 62, joined to the top members 49. These tube sheets 66 may bem'ade of castv iron and are preferably insulated on both sides, as byinsulation 69a, to prevent deterioration thereof. The tube sheets 60 areapertured to receive a bank of convection tubes 63 which substantiallyfill the convection chamber I3.

The hood I1 may rest upon the members 62 and 56 and is thus supported bythe framework above described. The hood I1 may have sloping sides'64which converge to the stack I 8.

The side buck stays 45 may be covered with a thin sheet material 65 suchas plaster board, so as to provide channels between the buck stays forthe passage of air.

foundations 2i, with the space below the floor 32 and burners 35. Thetop of the furnace on both sides of the hood l1 may be covered with asimilar material 61. An opening 68 may be provided to aior'd an airintake passage over the sheet material 65 and below the material 61.

The end of the convection chamber i3 may be closed by a door 16 whichmay be hung on a frame comprising sidemembers 1I, top member 'I2 andbottom member 13. The top member 12 may be secured to the end topmembers 56. The

bottom member 13 may b'e supported by beams 14 carried between end buckstays 46 and uprights 15 which also form the sides of the radiant tubedoor frame. The end buck stays 46 and uprights 15 may be joined at thebottom by a beam 16.

A pair of cross members 11 may extend between the end buck stays 46 anduprights 15 to form supports for peep-hole castings 18. Similar crossmembers 19 form frames on which entrance doorsare hung. Radiant tubedoors 8l may be hung between the uprights 15. It is to be understoodthat the end walls have openings corresponding to the frames abovementioned and that entrance doors and peep-hole castings may be omittedfrom one end of the furnace if desired. l

Fuel may be supplied to the burners '35 by fuel pipes which may extendthrough holes in the transverse beams 33 and may have nozzles 86 inalignment with the bores 36 of the various burners 35. Fuel is thuscaused to pass through the bores 36 of the burners 35 and to induce a owof air for combustion without other blower means. The burners may beregulated by controlling the supply of fuel.

` The radiant heat tubes 26 and the convection These channels mayconnect, by transverse passages 66 formed in the side tubes 63 areprovided with suitable headers by which they are connected-for oil iiowthrough the various tubes in series in the usual manner. The.

63 of the convection bank, for example one of the tubes in the top rowthereof, and passes in series through' all of the convection tubes 63wherein it receives heat from the combustion gases. Thence it passesthrough the radiant -where it is heated by radiant heat reradiated fromthe furnace walls and by convection heat from the combustion gases. Itmay be discharged from the lower tube of the radiant group. It is to benoted that the' oil is subjected to a moderate heat in the convectionbank and is subjected to a much more intense heat -in the' guide member29 is stream lined in the direction of gas flow so that the gases arecaused to pass,

into the convection chamber I3 with a minimumof turbulence. By thismeans the upper tubes of the radiant group and the lower tubes of theconvection bank are uniformly heated and a uniform distribution of gasesis obtained.

The location of the stack i8 over the convection chamber i3 permits thegases to be withdrawn without substantial change in direction, therebyutilizing the natural iiow of gases and eliminating the necessity for aforced draft or blower means. i

The provision' of a convection chamber of smaller cross section than thecombustion chamber causes the gases to flow over the convection tubes 63at an increased velocity which increases the efficiency of heat transferthereto.

Itis to be noted that the burners are in clined toward the side walls iland away from the radiant heat tubes 2. This prevents the intense heatof the dame from being applied directly to the radiant heat tubes andthereby causing local overheating or carbonization of the oil.

` By passing theair for combustion down over the outer surface of thewalls il, the walls are cooled and the air is preheated beforeapplication to the burners. Safety is also promoted as there is nooutside opening at the bottom of the Vfurnace through which inflammablematerial can enter.

The suspension of the convection tubes over the center of the combustionchamber and the support of the hood in a similar position presentsconstructional problems which have been solved by the frameworkdescribed above. It is evident that a considerable weight must besuspended at a 'point removed from the side buck stays. The upper andlower horizontal trusses, the vertical truss and the inclined members 48cooperate to form'a rigid support which is capable of transferring theload to the buck stays. It is to be noted that all supporting membersare located outside of the furnace walls where they are not 7 subjectedto thev heat of the combustiongases port the furnace rof or tubes and ahigh and expensive stack is not required.

Although a specific embodiment of the invention has been shown anddescribed for purposes of illustration, it is to be understood thatvarious changes and modifications may be made therein without departingIfrom the scope of the invention, which is to be limited only inaccordance with the following claims when interpreted in view of theprior art.

What is claimed is:

1. In a furnace of the class described, a vertically elongatedcombustion chamber, a bank of radiant tubes located in the centerthereof and dividing the combustion chamber into two sections, a. row ofburners arranged in the lower part of said chamber on each side of saidbank of tubes, a. convection chamber containing a bank of ,convectiontubes carrying hydrocarbon oil above said combustion chamber and inalignment therewith, and a stream lined guide member extendinglongitudinally above said bank of radiant tubes adapted to direct thegases into said convection chamber with a minimum of turbulence.

2. In a. furnace of the class described, a vertically elongatedcombustion chamber, a bank-of radiant tubes located in the centerthereof and dividing the combustion chamber into two sections, a row ofburners arranged in the lower part of said chamber on each side of saidbank of tubes, a convection chamber containing a bank of convectiontubes carrying hydrocarbon oil above said combustion chamber and inalignment therewith, said 'convection chamber being of smallercross-section than said combustion chamber and being joined thereto bysloping walls forming a passage for gases, and a stream lined guidemember extending longitudinally above said bank of radiant tubes adaptedto direct the gases into said convection chamber with a minimum ofturbulence.

3. In a furnace of the class described, in combination, side wallsdefining a combustion chamber, additional side walls defining aconvection chamber of smaller cross-section than said combustionchamber, said additional side walls being located above said rst wallsand joined thereto by slopingwalls, a bank of convection tubes in saidconvection chamber, hangers therefor, a

hood above said convection chamber, and supporting means forsaidadditional side walls, sloping walls, hangers and hood, comprising aframework entirely outside of said walls, said framework comprisingvertical buck stays outside of said rst walls and adjacent thereto, avertical truss adjacent said additional walls and supporting the same,upper and lower horizontal trusses joining the top and bottomrespectively of said vertical truss to said buck stays, and inclinedmembers extending from the bottom of said vertical truss to said buckstays along said sloping walls and supporting the same.

4. In a furnace of the class described, in combination, side wallsdening a combustion chamber, additional side walls dening a convectionchamber of smaller cross-section than said combustion chamber, saidadditional side walls being located above said rst walls and joinedthereto by sloping walls, a bank of convection tubes in said convectionchamber, hangers therefor, a hood above said convection chamber, and

supporting means for said additional side walls, sloping walls, hangersand hood, comprising4 a framework having vertical truss members andinclined truss members supporting said additional side walls and saidsloping walls respectively, vertical buck stays spaced from saidvertical truss members and joined to said inclined truss members, andtrusses connecting said vertical truss members to said buck stays.

5. In a furnace of the class described, an elongated combustion chamberhaving side and end walls, a foundation supporting said walls, aplurality of spaced radiant tubesheets carrying radiant tubes located ina row in the center of said combustion chamber, piers supporting saidtube sheets, a oor, burners projecting upwardly therethrough, andsupporting means for said floor comprising structural members supportedby said foundation and by said piers, said furnace having an air spacebelow-'said iioor for passage of air for combustion to said burners.

6. In a furnace of the class described, side and end wallsforming avertically elongated combustion chamber, a vertically extending bank ofhorizontal radiant tubes located in the center thereof and dividing thecombustion chamber into two sections, a row f burners spaced along thebottom of' said chamber on each side of said bank'of tubes, said burnersbeing inclined toward v the side walls for directing the iiame thereonso as to heat said walls to radiance, a convection chamber containing abank of lconvection tubes carrying hydrocarbon oil above said combustionchamber and in alignment therewith, said convection chamber being ofsmaller cross-section than said combustion chamber and being joinedthereto by sloping walls forming a passage for gases and a stream lined,guide member extending longitudinally above said bank of radiant tubesto direct the gases into said convection chamber with a minimum ofturbulence.

'7. In a furnace of the class described, a vertically elongatedcombustion chamber, a bank of radiant tubes located in the centerthereof and dividing said chamber into two sections, vertical tubesheets supporting said bank of tubes, said tube sheets being supportedat thef bottom 'and extending upwardly into said combustionA chamber, arow of burners on each side of said bank of tubes, said burners beingmounted in the lowerS .part of said chamber to direct the flame upwardlytherein, a convection chamber containing a bank of convection tubescarrying hydrocarbon oil above said combustion chamber and in alignmenttherewith, said convection chamber being of smaller cross' section thansaid combustion chamber and being joined thereto by sloping walls'forming a passage for gases 'and a. stream lined guide member supportedby said tube sheets and extending longitudinally above said bank ofradiant tubes to direct the gases into said convection chamber with aminimum of turbulence.

8. In a furnace of the class described, an elongated combustion chamberhaving side and end walls, a foundation supporting saidwalls, a.plurality of spaced radiant tube sheets carrying radiant tubes locatedin a row in the center of said combustion chamber, a central foundationsupporting said4 tube sheets, a door, burners projecting upwardlytherethrough and supporting means for said floor comprising structuralmembers extending between and supported by said first foundation andsaid central foundation, said furnace porting said tube sheets, a iloor,burners projecting upwardly therethrough and supporting means for saidfloor comprising structural members extending between and supported bysaid first foundation and said centralfoundation, said furnace having anair space below said floor for 'passage of air for combustion to saidburners and means forming an air passage at the outer side of said sidewalls through which air is caused to pass downwardly over said walls onits way to said air space. i

10. An upshot oil cracking still comprising, in combination, arectangular, elongated combustion chamber, a convection chamber abovesaid combustion chamber and formed as a continuation thereof, a bank ofhorizontal, longitudinally extending convection tubes carryinghydrocarbon oil substantially lling said convection chamber, transversetube sheets carrying said convection tubes, a. row of horizontal,longitudinally extending radiant heat tubes, said row extendingvertically below said convection tubes, a plurality of vertical bracketssupported only at the bottom, each bracket extending into supportingengagement with the entire row .of said radiant heat tubes, a row ofburners at the bottom of said combustion chamber and spacedlongitudinally thereof to direct the ame upwardly past saidcombination,a rectangular, elongated combustion chamber, a convection chamber abovesaid combustion chamber and formed as a continuation thereof, a bank ofhorizontal, longitudinally extending convection tubes carryinghydrocarbon oil substantially lling said convection chainber, transversetube sheets carrying said convection tubes, a row of horizontal,longitudinally extending radiant heat tubes, said row extendingvertically below said convection tubes, a foundation extendinglongitudinally beneath the central part of said combustion chamber, aplurality of vertical brackets supported at their bottom ends by saidfoundation, each bracket extending into supporting engagement'with theentire row of said radiant heat tubes, a row of burners at the bottom ofsaid combustion chamber and spaced longitudinally thereof todirect theflame 'upwardly past said radiant heat tubes onto the lower tubes ofsaid convection bank, and means to withdraw combustion gases from thetopof said combustion chamber in substantially a direct line with saidburners whereby the combustion gases pass through said furnace upwardly

